1. Field of the Invention
The present invention relates to an endoscope with channels into which medical instruments are to be inserted, and more specifically, to an arrangement of components constituting the channels in an operating section of the endoscope, and a mounting structure for fixing the channels in the operating section.
2. Description of the Prior Art
Typical endoscopes, having channels for medical instruments, comprise channel mouthpieces attached to an operating section, and channel ducts inserted in an insertion section and connected to the channel mouthpieces. The mouthpieces and ducts constitute the whole or part of the instrument channels.
Conventional fixing means for the channel mouthpieces and ducts are stated in Japanese Patent Disclosure No. 60-210233 and Japanese Utility Model Disclosure No. 61-48701. The disclosed fixing means both include a branch cover which has an opening portion. In connecting the channel ducts and mouthpieces, the branch cover is first slid so that the ends of the ducts are drawn out through the opening portion. Thereafter, the mouthpieces are connected to the ends of the ducts.
According to this method of connection, however, the branch cover can be moved over only a very short distance, due to restrictions on the branch structure and a demand for the miniaturization of the operating section of the endoscope. Further, it is very difficult to draw out the channel ducts fully from the opening portion. Thus, the conventional working method is troublesome and time-consuming.
According to the method of connection disclosed as aforesaid, the channel ducts may possibly be pulled during connecting work. An image guide, light guide, and other elements, inserted in the insertion section of prior art endoscopes, along with the channel ducts, have a relatively low tensile strength. Therefore, these elements may sometimes be damaged during the connecting work. Also, the channel ducts can be collapsed as the branch cover is moved.
Recently, there has been an increasing demand for endoscopes of lighter weight and smaller size. Accordingly, the fixing means for fixing the channel ducts to the operating section must be miniaturized. At the same time, the mounting structure for the channel mouthpieces must be strong enough to stand external force, which may be applied if the endoscope is dropped by mistake, or when attaching or detaching a syringe or other instruments to or from the mouthpieces.